Buckles of various structures are well known, each of which is comprised of a female member composed of a socket member and a male member composed of a plug member. Speaking of its basic structure, the socket member has engaging faces, while the plug member comprises arm portions which are adapted to be releasably inserted into the socket member, wherein engaging portions on the arm portions engage and disengage from the engaging faces of the socket member. Each socket member and plug member has a base portion at one side end thereof. Each base portion either has an integral slot, or a projection therefrom which when combined with the base portion forms a slot through which a strap or belt may be inserted and/or affixed therein. By engaging/disengaging the plug member from the socket member, the ends of a strap/belt can be connected to or disconnected from each other or to some other common element.
When an external force is applied to the exposed surfaces of the plug member which project out through the walls of the socket member, the forces resiliently deform the arms of the plug members causing them to disengage from the walls of the socket member. Therefore the plug member is easy to slip out of the socket member.
Additionally, there are buckles known in the art which offer a central cavity wherein multiple plug members are mutually inserted, such as the commonly called “five-point” harness of a child's car seat. However these devices are constructed to only work properly when all of the plugs are engaged—they fail, or can fail, in the performance of the design function if any plugs are not engaged.